A system and method are disclosed. Responsive to receiving a NACK message from the wireless terminal corresponding to the first and second transport data blocks, the first and second transport data blocks may be retransmitted to the wireless terminal over the MIMO channel. The front caster assemblies are bushed to the main chassis assembly and the rear caster assemblies respectively. SiO2 and calcium magnesium silicate, a cement composition containing said admixture, and a carbonation suppressing method by use of said cement admixture or cement composition. The amplified main and sub pixel image signals are digitalized and composed to generate composite image data.